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The points A, B, C, and D are on a number line

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Guest
 Post subject: The points A, B, C, and D are on a number line
 Post Posted: Wed Aug 20, 2008 9:11 am 
The points A, B, C and D are on a number line, not necessarily in this order. If the distance between A and B is 18 and the distance betwen C and D is 8, what is the distance between B and D?

1. The distance between C and A is the same as the distance between C and B.
2. A is to the left of D on the number line.

I think I understand the different cases of positioning these points. However, I thought the answer ic C, instead of E.
Can someone explain how to get to the answer.
Top 
TakingGMAT
 Post subject: The points A, B, C, and D are on a number line
 Post Posted: Mon Aug 25, 2008 7:19 am 
1) Only tells us that C is between A and B but nothing about D. Insufficient.

2) Tells us that A is to the left of D.
A B D or
--------------------------

A D B
--------------------------

Not sufficient.

1 and 2 together also not sufficient
Top 
Kaushik
 Post subject: Re: The points A, B, C, and D are on a number line
 Post Posted: Mon Aug 25, 2008 7:34 am 
Anonymous wrote:
The points A, B, C and D are on a number line, not necessarily in this order. If the distance between A and B is 18 and the distance betwen C and D is 8, what is the distance between B and D?

1. The distance between C and A is the same as the distance between C and B.
2. A is to the left of D on the number line.

I think I understand the different cases of positioning these points. However, I thought the answer ic C, instead of E.
Can someone explain how to get to the answer.


You can ans this question with statement 1 only ......
Top 
Raj
 Post subject: Re: The points A, B, C, and D are on a number line
 Post Posted: Mon Aug 25, 2008 3:19 pm 
Hi,

from (1), C has to be half way between A and B. So, AC and CB are each = 9. This does not give any info on D, hence not sufficient. Since CD = 8, D is with in AB but could be on either side of C. It is already clear that A is to the left of D

From (2), from above, this statement does not add any new information, we already know A is to the left of D. insufficient.

Taken together too, insufficient. Ans E.

Can you please share the official Answer.

Thanks,
-Raj.

Anonymous wrote:
The points A, B, C and D are on a number line, not necessarily in this order. If the distance between A and B is 18 and the distance betwen C and D is 8, what is the distance between B and D?

1. The distance between C and A is the same as the distance between C and B.
2. A is to the left of D on the number line.

I think I understand the different cases of positioning these points. However, I thought the answer ic C, instead of E.
Can someone explain how to get to the answer.
Top 
jwinawer
 Post subject:
 Post Posted: Thu Aug 28, 2008 11:53 pm 
Offline
ManhattanGMAT Staff


Posts: 76
Right. As the last poster said, we can deduce from statement 1 that C is halfway between A and B. But we cannot tell D is closer to A or closer to B.

With statement 1, we've got 4 possible layouts (not quite drawn to scale, but almost):

(1)
A --------------------------- B
---------------C------------D

(2)
A----------------------------B
-D-----------C

(3)
B ---------------------------A
------------- C------------D

(4)
B----------------------------A
-D-----------C


This is insufficient. Statement 2 doesn't help at all.

So the right answer is E.
Top 
navrajdhaliwal1
 Post subject: Re: The points A, B, C, and D are on a number line
 Post Posted: Sat Aug 22, 2009 2:36 pm 
Offline
Forum Guests


Posts: 1
Doesn't statement 2 that A is to the left of D, eliminate 3&4 below? What do you mean by "Statement 2 doesn't help at all"?

Answer still remains to be "E" as we cannot choose btw 1&2.

(1)
A --------------------------- B
---------------C------------D

(2)
A----------------------------B
-D-----------C

(3)
B ---------------------------A
------------- C------------D

(4)
B----------------------------A
-D-----------C
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